1. Field of the Invention
The present invention relates to a combination of a thyristor connection and a test device, in which the thyristor connection includes a plurality of thyristors each parallel connected to a voltage divider and the test device is provided for individual testing of the individual thyristors.
2. The Prior Art
A thyristor connection of the kind in question may, for example, be a thyristor valve for a high-voltage convertor, which valve comprises a large number of thyristors, sometimes several hundred, in series- and possibly parallel-connection. In parallel with each thyristor there is then a voltage divider, on the one hand for voltage distribution between the thyristors, and on the other for feeding a control device for the thyristor.
In the case of service inspection of such a thyristor valve, it is desirable to measure the blocking capability of the individual thyristors separately in both directions, which is done by measuring the leakage current in the thyristors at a certain voltage. The problem in this connection is, on the one hand, to connect a test voltage in a simple manner, and, on the other hand, to separate the leakage current through the thyristor from the leakage current through the voltage divider. This problem is primarily due to the fact that the control measurement of the many thyristors should take place without time-consuming detachment of parts in the system.